1. Field of the Invention
Embodiments of the present invention generally relate to a method for forming a silicon germanium (SiGe) layer.
2. Description of the Related Art
Micro-electromechanical systems (MEMS) are used in a wide variety of systems such as accelerometers, gyroscopes, infrared detectors, micro turbines, silicon clocks, and the like. Monolithic integration of MEMS and complementary metal-oxide semiconductor (CMOS) processing is a desirable solution in certain applications, such as detectors and displays, as the integration simplifies the interconnection issues. One easy approach for monolithic integration is post-processing MEMS on top of the driving electronics, since the standard fabrication processes used for preparing the driving electronics are not changed. However, post processing imposes an upper limit on the fabrication temperature of MEMS to avoid any damage or degradation in the performance of the driving electronics.
SiGe has been proposed as a structural material for MEMS that can be post-processed on top of standard CMOS driving and controlling electronics. A functional SiGe layer for use in microstructure devices may be over 2 micrometers thick and may be formed by depositing multiple layers of SiGe at 450 degrees Celsius. Therefore, an improved method for forming the SiGe layer is needed.